Combretastatin A4 is a vascular disrupting agent (VDA) that targets tumor vasculature to inhibit angiogenesis. Combretastatin A4 is a tubulin-binding agent that binds at or near the colchicine binding site of β-tubulin and inhibits tubulin assembly. This tubulin-binding agent was originally isolated from an African shrub, Combretum caffrum. Combretastatin A4 is cytotoxic to umbilical-vein endothelial cells (HUVECs) and to a range of cells derived from primary tumors and these cytotoxicity profiles have been used to assess several novel analogs of the drug for future development. Combretastatin A4 has antitumor activity by inhibiting AKT function. The inhibited AKT activation causes decreased cell proliferation, cell cycle arrest, and reduced in vitro migration/invasiveness and in vivo metastatic ability. Several studies in mice have shown that a single administration of combretastatin A4 (100 mg/kg) does not significantly affect primary tumor growth. However, repeated administration (12.5 – 25.0mg/kg twice daily) for periods of 10 – 20 days resulted in approximately 50% retardation of growth of ectopic Lewis lung carcinoma and substantial growth delay of T138 spontaneous murine breast tumors. In clinical studies, Combretastatin A4 has been well tolerated in patients at doses up to 56 mg/m2, following a protocol of five daily 10-minute intravenous infusions every 21 days. The disodium combretastatin A4 phosphate prodrug is currently undergoing clinical trials in the UK and USA.

Exisulind (tentative trade name Aptosyn) is an antineoplastic agent, which was originally developed by Cell Pathways. This drug is an inhibitor of phosphodiesterase (PDE) isozymes: PDE5 and PDE4. Inhibition of PDE5 appears to be pharmacologically relevant, which leads to increase cGMP and activate protein kinase G at doses that induce apoptosis, whereas cyclic AMP levels were not changed. Exisulind has been in phase III clinical trials for the treatment of Non-Small Cell Lung Cancer and for the treatment of polyps in patients who have familial adenomatous polyposis (Colorectal Cancer and Small Intestine Cancer). In addition, this drug was in phase II/III for the treatment of Prostate Cancer, however, there studies have been discontinued.

The BET-bromodomain inhibitor OTX015 (MK-8628) was initially developed by Mitsubishi Tanabe Pharma Corporation, but then was licensed by OncoEthix, privately held biotechnology company. OTX015 is a selective bromodomains: BRD2, BRD3, and BRD4 inhibitor and inhibits their binding to AcH4. Bromodomains have an important role in the targeting of chromatin-modifying enzymes to specific sites, including methyltransferases, HATs and transcription factors and regulate diverse biological processes from cell proliferation and differentiation to energy homeostasis and neurological processes. OTX015 has potent antiproliferative activity accompanied by c-MYC down-regulation in several tumor types, and has demonstrated synergism with the mTOR inhibitor everolimus in different models. Oral administration of OTX-015 markedly inhibited tumor growth and reduced tumor volume. OTX015 is currently in Phase 1b studies for the treatment of hematological malignancies and advanced solid tumors such as Triple Negative Breast Cancer, Non-small Cell Lung Cancer, Castrate-resistant Prostate Cancer (CRPC) and Pancreatic Ductal Adenocarcinoma. In addition, OTX015 was in phase II for the treatment of Glioblastoma Multiforme, but there were not detected clinical activity of the drug in the treatment populations and trial was closed.

Tarenflurbil (Flurizan or R-flurbiprofen) is the single enantiomer of the racemate NSAID flurbiprofen. Tarenflurbil is a first in class, selective amyloid-beta42 (A42) lowering agent (SALA), which acts by modulating the activity of gamma-secretase, an enzyme that converts amyloid precursor protein to amyloid-beta. The reduction of A42 may prevent the development of the amyloid plaques thought to be a key pathological process associated with Alzheimer’s disease. For several years, research and trials for the drug were conducted by Myriad Genetics, to investigate its potential as a treatment for Alzheimer's disease. In a brief statement issued June 30, Myriad Genetics reports that tarenflurbil (Flurizan) failed to have a significant effect in a phase 3 trial of patients with mild Alzheimer's disease (AD). The failure of Flurizan™ is generally attributed to its insufficient pharmacodynamics, i.e., inadequate ability to penetrate the brain and engage its target protein at doses sufficient to yield an effect. Two additional Phase 3 trials were terminated and further development of Flurizan™ was discontinued. Separate clinical development of Flurizan™ for prostate cancer has also been discontinued following negative Phase 2 results. Tarenflurbil activates c-Jun N terminal kinase, increases AP-1 binding to DNA, and downregulates cyclin D1 expression, resulting in the arrest of tumour cells in the G1 phase of the cell cycle and apoptosis. This agent also affects the expression of nuclear factor kappa B, a rapid response transcription factor that stimulates the immune response to tumour cells. Tarenflurbil does not inhibit the enzyme cyclooxygenase. The Fraunhofer Institute for Molecular Biology and Applied Ecology is currently developing tarenflurbil for the treatment of relapsing, remitting multiple sclerosis.

MK-2866 (Gtx-024) is a selective androgen receptor modulator (SARM) for treatment of conditions such as muscle wasting and osteoporosis. It is a non-steroidal agent with anabolic activity designed to work like testosterone, thus promoting and/or maintaining libido, fertility, prostate growth, and muscle growth and strength. Mimicking testosterone's action, this agent may increase lean body mass, thereby ameliorating muscle wasting in the hypermetabolic state of cancer cachexia.

Alvocidib (also known as Flavopiridol or HMR-1275) is a flavonoid alkaloid CDK9 kinase inhibitor under clinical development for the treatment of acute myeloid leukemia, by Tolero Pharmaceuticals, Inc. As a broad spectrum CDK inhibitor, Alvocidib can inhibit cell cycle progression in either G1 or G2 and induces G1 arrest in either MCF-7 or MDA-MB-468 cells by inhibition of the CDK4 or CDK2 kinase activity. Alvocidib exhibits potent cytotoxicity against a wide variety of tumor cell lines (LNCAP, HCT116, A2780, K562, PC3, and Mia PaCa-2) with IC50 values ranging from 16 nM for LNCAP to 130 nM for K562. Administration of Alvocidib at 7.5 mg/kg for 7 days displays slight antitumor activity against P388 murine leukemia, and active against the human A2780 ovarian carcinoma implanted sc in nude mice). Alvocidib treatment at 1-2.5 mg/kg for 10 days significantly suppresses collagen-induced arthritis in mice in a dose-dependent manner, by inhibiting synovial hyperplasia and joint destruction, whereas serum concentrations of anti-collagen type II (CII) Abs and proliferative responses to CII are maintained. Tolero Pharmaceuticals Inc. announced that the FDA has granted orphan drug designation for Alvocidib, its cyclin-dependent kinase small molecule inhibitor, for the treatment of patients with acute myeloid leukemia.

BMS-690514 is a potent, reversible oral inhibitor of epidermal growth factor receptor (EGFR/HER-1), HER-2 and -4, and vascular endothelial growth factor receptors (VEGFRs)-1 to -3 offering targeted inhibition of tumour growth and vascularisation in a single agent. Bristol-Myers Squibb was developing BMS 690514, as an oral treatment for cancer. BMS-690514 had being in phase II for the treatment of breast cancer; non-small cell lung cancer, but later these studies were discontinued.

Motesanib (AMG 706), a novel nicotinamide, was identified as a potent, orally bioavailable inhibitor of the VEGFR1/Flt1, VEGFR2/kinase domain receptor/Flk-1, VEGFR3/Flt4 and Kit receptors. Motesanib was expected to reduce vascular permeability and blood flow in human tumours. A phase III trial of motesanib in combination with paclitaxel and carboplatin in non-squamous NSCLC has been terminated by Takeda and subsequently the development was discontinued. Motesanib has also been investigated up to phase II in breast, thyroid, colorectal and gastrointestinal stromal tumours. However, development has been discontinued in these indications.

ARN-810 (GDC-0810) is a novel, orally bioavailable, estrogen receptor antagonist that induces proteasomal estrogen receptor degradation in breast cancer cell lines at picomolar concentrations and tumor regression in tamoxifen-sensitive and resistant BC xenograft models. Results from a first-in-human phase I/IIa study of ARN-810 indicate that it is tolerable and may benefit some postmenopausal women with advanced estrogen receptor-positive breast cancer. Development of ARN-810 was discontinued.

Bevirimat (3-O-(3',3'-dimethylsuccinyl) betulinic acid or MPC-4326 or PA-457) potently inhibits replication of both WT and drug-resistant HIV-1 isolates and demonstrate that the compound acts by disrupting a late step in Gag processing involving conversion of the capsid precursor (p25) to mature capsid protein (p24). Bevirimat inhibits replication of both wild-type and drug-resistant HIV-1 isolates in vitro, achieving similar 50% inhibitory concentration values with both categories. Serial drug passage studies have identified six single amino acid substitutions that independently confer bevirimat resistance. These resistance mutations occur at or near the CA-SP1 cleavage site, which is not a known target for resistance to other antiretroviral drugs. Bevirimat has been in phase 2 trial for the treatment of HIV infections. Bevirimat has demonstrated a consistent pharmacokinetic profile in healthy volunteers and HIV-infected patients. The demonstration of an antiviral effect following a single oral dose of bevirimat validates maturation inhibition as a potential target for antiretroviral therapeutics in humans.